Rheostat.



CH. BEACH.

RHEOSTAT.

APPLICATION mso ocT. 25. |915.

Patented Oct. 17, 1916.

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UNITED STATES PATENT OFFICE.

CHESTER H. BEACH. OF RACINE, WISCONSIN, ASSIGNOR TO WISCONSIN ELECTRIC COM?ANY. 0F RACINE, WISCONSIN. A CORPORATION 0F WISCONSIN.

Appiicaiion ined october' 25. 1915.

To all :el: om it may conf-ern Be it known that l, (Horaria: ll. Brixen, a citizen of the United States, residing at ltarine. in the count)v of llacine and State ot' ll'iseonsin. have invented a certain new and useful liiiprovement iii hheostats. ot' which the following is a full, ilear, concise, and exact description. n

My invention relates to improvements in rheostats.

The object of the invention is to provide a 'rheostat wliieh may be convcniwilly-operated to control a small motor siieh as a sewing machine motor.

ln the accompanying drawings, I have illustrated two embodiments of the invention, in both of which the rheostat is operated by foot pressure. llowever, it may be operated iii other ways. i Figure 1 is a side elevation otl one forni of rlieostat, which rests on the lloor and is o ierated by t'oot pressure. Fig. :l is a top plan view thereof. Fig. il is an enlarged sectional elevation on tbe line 3 3 of Fig. 2. Fig. 4 is a plan view on the saine scale with tlietop removed.. Fig. 5 .is an elevation of a modified eonstruetion,.in which the rheostat is suspended.

The first rheostat, which is indieated by reference 4character 1, is su )ported on a projecting spindle 2, provided with a base plate 3, the rheostat being yicldingly held above the base by a helical spring l. -The base plate i's provided with a rubber pad 5 to prevent slipping. The rheostat as a whole, is foi-eed downwardly against the artion of a spring l, by means ot' a suitable lever or foot pedal 1'. secured to the rheostat at one end alid constructed at the other end with an integral cross arm provided with a pair of rubber pads S. wliii'h rest directly on the floor. 'llie middle part of the foot pedal is enlarged and provided witlreoncentric ridges il to prevent slipping` of the foot. ln the normal position shown in Fig. l. thefcireuit is open, as hereinafter explained and the sewing mai-bine motor at rest. ln order to start the machine the opei'- ator merely presses down with the ioot, whereulmli the motor starts and the 'speed thereof increases as the rlieostat is pressed lower. l

The inaiu body of the rheostat consists of a. eylindrieal member 1() made of insulating Specification of Letters Patent.

serial No. 57,875.

material. lt is provided with a plurality of grooves llaround its periplier ,said grooves beingY parallel to the main n xis of the cylinder. The resistor 12 consists of a line Wire of high resistance, which is wound into helieal form and then wound back and forth in the ,q1-wives as shown in Fig'. 5. The grooves communicate with cach other at 'the top and bottom by means of short connecting passages 13. 14. pluralitr of resilientI strips l5, lll, 17,' 1S. 19, 20, .21 are provided. These conductors are arranged radially on top of the insulating support. their inner ends being bent down and arranged parallel within the central opening of the Cylinder, their parallel portions beingreeeived within suitable slots '22. The strip 15 has its lower part bent under, whereby the vertical length thereof is sprung,Y away from the base of the Channel within which it is received. The

horizontal portion thereof has secnredtheres to a terminal pin 23. Contact sti-ip 21 is arranged with its horizontal portion resting on a metal clip 24, which carries a second terminal pin 25. The conducting strips 16,'

1T, 1S, 19, 30. 21 are generally similar, each ha ving` a verti xal portion Q6 extending down' wardly as shown lnFig. 3, and provlded with a curved projection .27 at the lower end thereof, which forms a yielding contact. The horizontal parts thereof are arran ed radially. as stated, the outer end of each `e ing formed into a hook 29, which rests in one of the passages 13, previously mentioned. 'lhe resistor is looped mier the successive hooks and thereby maintains itself in .electrical contact therewith. v

'llie parallel downward extensions 2G successively shorten, beginning with contact 1G and extending around to contact 21. The projections 2T thereon are adapted to be engaged successively by a sliding contact 30, consisting of a ring of metal, s un down over an insulating button 31, carried by the spindle 2. The contact 30 is always in engagement with the vertical part of the conducting strip 15, whereby as the ,rheostat as a( whole is movedA downwardly by the operatorsl foot. as previously explained, the contact 3U engages successively the projecting lower ends of the various contacts 1G, 17, 18, 19, 20, 21. in the order named. Engagement between the contact 3() and the lower end of the metal strip 16 results in Closing the eirlatented Oct. 17, 1916.

ico

cuit through the entire length of resistance wire, thereby starting the motor slowly. lvhen the contact 1T is engaged, the length of resistance wire in the circuit is reduced, thereby speeding up the motor and when contact is made with the last and shortest strip 2l, all the resistance is out of circuit and the motor runs at full speed. The return circuit from the strip il is made through the metal clip 2l and contact 'pm 2 previously mentioned. Contact 3() in its upward movement is always in engagement with at least one of the yielding contacts 2T, that is to say, hcforesaid contact leaves the inw'ardly arched lower end o1' one strip, 1t engages the arched end of the next strip, so that the circuit is never opened.

The relation between the insulating cylinder 1 and the spindle 2, over which it slides, is maintained by a pair of metal plates 32, 33, which fit over the ends thereof, but are insulated therefrom by disksof insulating material 34. The parts are held together by a. plurality of screws 35, which pass downwardly, as shown in in Fig. 3 and screw' into the foot pedal 6. An ornamental outer casing 36 is provided which is made preferably of perforated metal to permit ventilation of the rheostat. Said casing is retained within the flanged over ends 37, 37 of the upper and lower metal plates 32, 33. The spindle 2 is guided through a centralopening in said upper plate and through'a metal thimble 3S, secured to the lower plate andfhaving a central opening, as shown. The spring l is received within said thilnble and bears against the upper wall thereof and against a. Washer 39 surrounding the lower end of the spindle 2. Said spindle is secured to the-- base 3 by means of a screw 40 received within a. vrecess in the under part of thebase.

Connections from the rheostat to the motor are made through any suitable attachment plug-41 and flexible leads 4Q.

' In Fig. 5 I 'have illustrated a somewhat 4modified construction, the main body of the rheostat being substantially the same as that previously described, but means being provided whereby it may be suspended from the frame of the sewing machine 43, or other suitable support, by means cfa chain 44 or a cord, and operated by means of a further chain or cord 45, attached to the usual vtreadle of the machine, which is not otherwise used, where an electric motor is femploved. The chain 44 is secured to the' top of the main central spindle 46 of the rheo stat by means of a bail 47. The downward pull is communicated to the frame of the rheostat through a bracket 48:` which is se- Y cured in place by the same screwswhich in the preceding form were used to secure the rheostat to the foot treadle. The downward pressure of the operators foot pulls downward the entire body of the rheostat against the action ot' the spring 49, the central spin dle being supported by the ehainl-l. 'l`he motor is therefore controlled by the same relative'movement of the parts.

The. rheostat is small. light and easily actuated. lt nerd not necessarily be opel'- ated by toot power as it may be operated equally well by hand power, where thc operator has a hand available. lt is not coulincd to use with a sewing machine motor, hut ,may he used in various other relations. l do not desire therefore. to limit myself to the structural details described herein, except where limitations are imposed in the appended claims.

Yhat l claim as new and desire lo obtain hy Letters latent of the United States is:

1. rlieostat comprising a body of insulating material, having a central opening and having a plurality ot' contacts arranged in said opening at successively increasing distances from the one end thereof, a l'esistor assm'iated with said contacts, and a spindle slid-ably mounted in said opening, said spindle carrying a contact arranged to engage said first mentioned contacts in succession.

2. A rheostat comprising an insulating body, a resistor' thercon,`contacts for varying the effective length of said resistance, a spindle projecting into said insulating body and carrying a contact cooperating with said irst contacts, means for supporting said spindle and a spring for supporting said rheostat on said spindle to vary the resistance. i

3, A rheostat comprising a cylindrical insulating base, having parallel slots around the circumference, a continuous helical re other end thereof, an. additional Contact connected to a second terminal conductor,`

and a. sliding contact always in engagement with said additionalcontact and arranged' to engage the reina ining contacts in succession. i

4. A rheostat consisting Ikof a cylindrical block having outer longitudinal parallel grooves.l a plurality of contacts at one endof said block, each having a projecting end constituting a hook arranged between the ends of adjacent grooves, va'nd a-helical resistor wound back and'forth in said grooves and (engaging said hooks. said helix being'under tension, whereby it makes the necessary electrical contact with said hooks without auxiliary clamping means and tends to hold said contacts iriplace. Y

5. A rheostat consisting of a cylindrical block having. outer longitudinal parallel grooves, a plurality of contacts each having one end projecting into a central opening` in said block and having the outer end Drovided with a hook, a resistor wound back and forth in sai grooves and engaging said hooks to make electrical` contact therewith and hohl said contaotsnigainst the end of Said blvk and an outer casing forlpositively locking said contacts against misplacement and for incasing said resistor.

In a device of thc class described1 a central spindle having u. Contact ring thereon, an insulating block surrounding said ring, contacts arranged on said block to be engaged successively by said ring, a spring surrounding.;` said spindle, and means for guiding said spindle at both ends of said block, whereby relative sliding movement of said block and said spindle is effective to close the successive contacts.

In a device of the class described, a base of insulatingr material having a central opening', a plurality of conductingr strips arranged radially with their inner ends received within said opening, a resistor engagingr the outer ends thereof, an insulating washer at each end of said base, a perforated casing surrounding said resistor, end caps at each end of said base and screws passing,y through said end caps and said base to secure the parts in place.

vIn witness whereof, I hereunto subscribe my name this 12th day of October A. D.,

CHESTER H. BEACH. 

